1. Field of the Invention
The present invention relates to a numerical control device including a display part for displaying information for evaluation of a machining process.
2. Description of the Related Art
A numerical control (NC) device is used for performing a desired machine process by driving a plurality of drive shafts of a machine tool in accordance with a machining program. The numerical control device is designed to calculate a command coordinate corresponding to a machining program (hereinafter referred to as a “program coordinate”), based on a command position of each drive shaft (hereinafter referred to as a “program position”) which is included in the machining program and for which interpolation has yet to be carried out, and on machinery information of the machine tool (for example, a relative position of a machining point in the machine tool). A trajectory corresponding to the machining program (hereinafter referred to as a “program trajectory”) is then obtained by connecting each coordinate with a given selected shape, such as straight lines or curves.
Interpolation is carried out based on the obtained program trajectory, a command velocity and other machining conditions, and a command coordinate after the interpolation (hereinafter referred to as a “command coordinate”) is calculated. A command trajectory after the interpolation (hereinafter referred to as a “command trajectory”) is then obtained by connecting each command coordinate after the interpolation with a given selected shape. Accordingly, interpolation which depends on a command velocity and other machining conditions is carried out in order to obtain the command trajectory in relation to the program trajectory, and the trajectories before and after the interpolation do not necessarily match each other. As a result, an expected shape sometimes cannot be obtained by machining. JP-A-6-59717 and JP-A-2011-22666 disclose a numerical control device including a display part for displaying trajectory data. However, a conventional evaluation method for evaluating a machining process includes comparing errors in shapes between a command trajectory after the interpolation and an actual trajectory of a tool. In addition, the evaluation method is mainly performed to check an adjustment effect of parameters which are set for the numerical control device in order to control movement of drive shafts. Therefore, if errors result from the interpolation or the machining program, it is difficult to identify the cause of the errors and find a solution thereto.
According to the present invention, a numerical control device including a display part for displaying necessary information to evaluate machining accuracy by taking into account changes in commands before and after interpolation is provided.